GNGTS 2013 - Atti del 32° Convegno Nazionale

Kinematic model of active extension across the Umbria-Marche Apennines fromGPS measurements: fault slip-rates and interseismic coupling of the Alto Tiberina low-angle normal fault L. Anderlini 1,2 , E. Serpelloni 3 , M.E. Belardinelli 1 1 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Italy 2 Dipartimento di Fisica, Settore di Geofisica, Universita di Bologna, Italy 3 Istituto Nazionale di Geofisica e Vulcanologia, Centro Nazionale Terremoti, Roma, Italy Introduction. The growing number of continuously recording GPS stations over Italy, particularly during last 5 years, gives the possibility to detect, with higher accuracies and precisions than in the past, gradients of ground deformation rates across major fault structures. Using a kinematic block-modeling approach it is possible to model the observed gradients in order to estimate fault parameters and long-term slip-rates, inferring new information useful to evaluate the seismic potential of a region. The Umbria-Marche Apennines are characterized mainly by SW-NE oriented extensional deformation (see Fig. 1), as documented by geodetic (D’Agostino et al. , 2009), geologic (Tondi, 2000; Boncio and Lavecchia, 2000a) and seismological (Pondrelli et al. , 2006) data. Most of major historical and instrumental earthquakes occurred mainly on the western side of chain, Fig. 1 – Seismotectonic framework of central Italy, red arrows show observed GPS velocities, black lines indicate bounds of the elastic blocks, blue dots represent instrumental seismicity, and also available focal mechanisms are shown; orange lines are DISS fault sources and blue lines are fault boxes from Lavecchia et al. (2002). 147 GNGTS 2013 S essione 1.2